Synthesis and properties of novel copolymers of poly(ether ketone biphenyl ketone ether ketone ketone) and poly(ether ketone sulfone amide)

The monomer containing sulfone and amide linkages, namely N,N'-bis(4-phenoxybenzoyl)-4,4'-diaminodiphenyl sulfone (BPBDAS), was conveniently prepared by the condensation of 4,4′-diaminodiphenyl sulfone with 4-phenoxybenzoyl chloride in N,N-dimethylacetamide (DMAc). Novel copolymers of poly (ether ketone biphenyl ketone ether ketone ketone) and poly (ether ketone sulfone amide) were synthesized by the modified Friedel-Crafts acylation solution copolycondensation of isophthaloyl chloride (IPC) with a mixture of 4,4′-bis (4-phenoxybenzoyl) biphenyl (BPOBBP) and BPBDAS. The copolymers obtained were characterized by different physico-chemical techniques. The copolymers with 10–25 mol% BPBDAS are semicrystalline and had increased T _gs over the conventional PEEK and PEKK due to the incorporation of rigid biphenylene moieties, sulfone and amide linkages in the main chains. The copolymers III and IV with 20–25 mol% BPBDAS had not only high T _gs of 182–185 °C, but also moderate T _ms of 337–339 °C, having good potential for the melt processing. The copolymers III and IV had tensile strengths of 102.2–103.5 MPa, Young’s moduli of 2.65–2.76 GPa, and elongations at break of 17.5–18.9 % and exhibited high thermal stability and excellent resistance to organic solvents.